The invention relates to new nitrogen additives which can be used as agents for decreasing the cloud point of hydrocarbon middle distillates (fues oils, gas oils), as well as to compositions of middle distillates containing said additives.
The oil distillates of interest in the invention are middle distillates (fuel oils, gas oils) whose distillation range (standard ASTM D 86-87) is between 150.degree. C. and 450.degree. C. Gas oils which are of more particular interest distill between an initial temperature from 160.degree. C. to 190.degree. C. and a final temperature from 350.degree. C. to 390.degree. C.
A great number of products sold on the market are designed to improve the limit filtrability temperature and the pour point of oil cuts of high paraffin content, for example:
polymers based on long chain olefins, PA0 copolymers based on alpha-olefins, PA0 ethylene-vinyl acetate copolymers, PA0 N-acylaminoethylesters of acid-containing polymers, or PA0 halocarbon compounds.
These products act on the kinetic crystallization phenomena and change the crystal size, thus allowing the use of the suspension at a lower temperature without plugging of the pipes and the filters. The above products do not modify the temperature at which the first paraffin crystals appear. As a matter of fact, it has been considered, up to now, that this temperature was dependent on the molecular weight and the composition of the paraffins and on the nature of the solvent.
A decrease of the cloud point of middle distillates (particularly gas oils) by means of an additive would be highly beneficial to the refiners, since it would make it possible, without changing the distillation diagram, to comply with the standards which are presently subject to an increasing severity.